How should we conceptualize the use of missile-equipped uninhabited aerial vehicles (UAVs or “drones”) in the U.S. “war on terror”? If violence of this kind is to be effectively restrained it is necessary first to establish an understanding of its nature. To this end, it is useful to focus on those theatres of the war where drones are the dominant platform for violence (such as in Pakistan, Yemen, and Somalia), rather than where they support primarily ground-based efforts (such as in Afghanistan and Iraq). The analysis in this article is presented in two parts. The first part considers whether drone strikes are better conceptualized as acts of war or of law enforcement. If it is difficult to conceptualize drone-based violence as acts of war, then such violence may not be captured by the traditional jus ad bellum (just resort to war) framework within just war theory. And if drone strikes do not constitute a law enforcement practice, the peacetime ethics of criminal justice may not apply either. One possible solution is to develop and apply a legitimization framework of jus ad vim (just resort to force) in which vim is “force short of war,” although this depends upon the sustainability of a vim/bellum distinction.

The second part of the article suggests a fourth alternative concept of drone-based violence—vis perpetua (perpetual force)—and explores the ethical implications thereof. At the strategic level, drone strikes pose a moral problem if, as a form of risk management, they are intended to continue indefinitely. At the individual level, the lack of physical risk experienced by drone operators serves to relieve domestic political concerns about casualties among U.S. combatants. However, a corollary of so reducing the “friction” that counteracts perpetual force is that physical risk is effectively transferred away from U.S. combatants and toward foreign noncombatants living in the places where drone strikes occur. The injustice of such systematic endangerment of innocents is compounded by the possibility that drone-based violence carries no promise of victory and, thereafter, peace.